1. Field of Invention
This invention relates generally to cardiovascular devices, intended to occlude circulatory communications that may be or may become detrimental to patient health. More specifically, this invention encompasses accelerated release methods for an occlusion methodology involving sutureless delivery of an occlusion patch to a physiological opening.
2. Background
Compromised health may be caused by cardiovascular structures that adversely affect the proper flow of blood. Such structures may be abnormalities that affect a relatively small subset of the population, and others may be common and not normally pathogenic, yet become so due to extrinsic causes. Examples of the former are congenital heart defects including Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), and Patent Ductus Arteriosus (PDA), and examples of the latter are normal cardiac structures such as Patent Foramen Ovale (PFO) and Left Atrial Appendage (LAA). The above mentioned structures are generally characterized by a hole or opening, which allows for fluid communication between cardiac chambers and/or blood vessels.
Congenital heart defects can cause an abnormal distribution of cardiovascular pressures and the dilution of oxygenated blood, which can significantly reduce cardiac pumping efficiency. Normal cardiac structures can sometimes become pathogenic by functioning as a location of blood clot formation, as in the LAA, or as a path by which blood clots can travel to the brain, as in PFO. Additionally, modifications to cardiovascular structures, which can cause anomalous blood flow, may be intentionally created by a physician in order to accommodate a certain procedure or to elicit some therapeutic effect. An example of this is the creation of a hole in the cardiac wall, in order to insert catheters and have direct access to cardiac structures such as valves. One treatment option for such cardiovascular structures is to occlude the communication using a surgically or percutaneously implanted device. Patents have been issued for several such devices including U.S. Pat. No. 3,874,388 to King et al., U.S. Pat. No. 4,917,089 to Sideris, and U.S. Pat. No. 5,725,552 to Kotula et al. Although these patents vary in many ways, their common attribute is that they include the concept of a metallic frame, intended to provide permanent support that maintains the device on the cardiac structure. Although metallic occlusive devices are widely used, they carry certain risks including wire fractures, perforations, and potential leaching of toxic materials.
Devices containing no metallic materials can potentially eliminate some of these risks. Non-metallic occlusive devices have been proposed in the prior art, including: U.S. Pat. No. 5,192,301 to Kamiya et al., which appears to describe a deformable plug made from a shape memory polymer; U.S. Pat. No. 5.634,936 to Linden et al. which appears to describe a device that includes a “self-hardening” polymeric material; U.S. Pat. No. 6,238,416 to Sideris, which appears to describe a balloon deliverable polymeric device; and U.S. patent application Ser. No. 11/728,906 to Opolski et al. describing a device using a polymeric wire frame. To the inventors' knowledge, only one of these patents covers a device that is in commercial use; this is U.S. Pat. No. 6,238,416 to Sideris, which patent is hereby incorporated by reference herein in its entirety.
The Sideris '416 patent describes a method of suture-less patch placement to correct a physiological opening in the form of a heart defect comprising a hole. The patch is first attached to a deflated balloon which is placed distally to the hole using special delivery catheters. The balloon is inflated with fluid and the patch is positioned upon the hole. After a specified coagulation/endothelialization period of time, the balloon is deflated and removed through a small hole in the patch, leaving the patch to occlude the defect. Practically, the coagulation/endothelialization process serves to attach/adhere the patch onto the cardiac tissue. This process requires an extended period of time, which can be dependent on the patch material. The extended period of time required for completion of this process makes the procedure inconvenient compared with other occlusive techniques and devices.